Buck converters are commonly used to change the voltage or polarity of a DC power supply. Typically, a buck converter will have several phases connected in parallel; each phase having two switches (top and bottom switches) connected to an inductor. Such multiple phase buck converters are well known in the art and are commonly used for providing regulated DC power for microprocessors, telecommunications electronics and the like.
In recent years it has been discovered that efficiency and transient response of a multiple phase buck converter can be improved by coupling the inductors of several phases. Coupling inductors tends to decrease output current ripple, and thereby reduce the conduction loss in the switches. However, the extra conductor windings required for the coupled inductors increases the electrical resistance of the circuit, which adversely affects the energy conversion efficiency. Also, the use of a winding in the output circuit requires an additional copper layer on the printed circuit board, which tends to increase the cost.
It would be an advance in the art of voltage converter design to provide a multiple phase buck converter or boost converters having coupled inductors with exceptionally low output resistance. It would be particularly beneficial to provide coupled inductors that do not require multiple copper layers for the electrical conductors. Such a voltage converter would have exceptionally high power conversion efficiency, fast transient response, and lower cost.